Device for the implantation and fixation of prosthetic valves

ABSTRACT

A device for the transvascular implantation and fixation of prosthetic heart valves having a self-expanding heart valve stent ( 10 ) with a prosthetic heart valve ( 11 ) at its proximal end is introducible into a patient&#39;s main artery. With the objective of optimizing such a device to the extent that the prosthetic heart valve ( 11 ) can be implanted into a patient in a minimally-invasive procedure, to ensure optimal positioning accuracy of the prosthesis ( 11 ) in the patient&#39;s ventricle, the device includes a self-expanding positioning stent ( 20 ) introducible into an aortic valve positioned within a patient. The positioning stent is configured separately from the heart valve stent ( 10 ) so that the two stents respectively interact in their expanded states such that the heart valve stent ( 10 ) is held by the positioning stent ( 20 ) in a position in the patient&#39;s aorta relative the heart valve predefinable by the positioning stent ( 20 ).

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a device for the transvascularimplantation and fixation of prosthetic heart valves having aself-expanding heart valve stent with a prosthetic heart valve at itsproximal end.

Background Information

A device of this type is, in principle, known to medical technology. Atpresent, biological or mechanical valve models are available tosubstitute for human heart valves which are usually fixedly sewn intothe bed of the heart valve during a surgical procedure through anopening in the chest after removal of the diseased heart valve. In thissurgical procedure, the patient's circulation must be maintained by aheart-lung machine, whereby cardiac arrest is induced during theimplantation of the prosthetic heart valve. This consequently makes thesurgical procedure a risky one coupled with the associated risks for thepatients and a lengthy post-operative treatment phase. In particular,such a procedure cannot be performed on patients whose hearts arealready too weak.

Minimally-invasive treatment procedures of recent development arecharacterized in particular by requiring a considerably shortenedduration of anesthesia. One approach provides for implanting aself-expanding prosthetic heart valve with an artificial heart valve anda collapsible and expandable stent connected to the heart valve into thehuman body by means of an appropriate catheter system. The cathetersystem is used to guide such a self-expanding prosthetic heart valvethrough a femoral artery or vein to its site of implantation at theheart. After reaching the site of implantation, the stent, whichconsists for example of a plurality of self-expanding stent segmentswhich can be bent relative one another in the longitudinal direction,can then be successively expanded. Following the expansion, anchoringhooks can for example support the anchoring of the prosthetic heartvalve at least in the respective blood vessel close to the heart. Theactual prosthetic heart valve itself is thereby in the direct proximalarea of the stent.

Known for example from the DE 100 10 074 AI printed publication is adevice for fastening and anchoring prosthetic heart valves, which isessentially formed from wire-shaped interconnected elements. The deviceprovides for using various different arched elements in order to attaina secure retention and support for the prosthetic heart valve. To thisend, the device described in this printed publication makes use of threeidentical pairs of arched elements, offset from one another by 120°.These arched elements are interconnected by means of solidarticulations, whereby the solid articulations fulfill the function ofpivot bearings. Additional arched elements bent opposite to each otherare furthermore provided which form rocker arms as equal in length aspossible in order to achieve a secure anchoring of the arched elementseven when subject to peristaltic actions on the heart and blood vesselsand a solid sealing for an implanted and anchored prosthetic heartvalve.

In the known solutions, however, there is a risk of heart valve implantmalalignment. This essentially refers to the exact positioning andangular adjustment of the prosthetic heart valve to be implanted. Inparticular, it is only with immense skill on the part of the personperforming the implantation—if at all—that a stent with the prostheticheart valve at its proximal end winds up being positioned so preciselyin the proximity of the patient's diseased heart valve that bothsufficient lateral positioning accuracy as well as a suitable angularposition to the prosthetic heart valve can be optimally ensured. Theknown solutions are also only conditionally suitable for explantingimproperly or incorrectly positioned prosthetic heart valves. Such aprocess is usually only possible with great effort; in particular, afurther surgical procedure is required.

Among other complications, an implantation malalignment of a less thanoptimally positioned prosthetic heart valve can lead to, for example,leakage or valvular regurgitation, which puts a substantial burden onthe ventricle. Should, for example, a prosthetic heart valve beimplanted too high above the actual heart valve plane, this can lead toocclusion of the coronary artery origination (coronaries) and thus to afatal coronary ischemia with myocardiac infarction. It is thereforeimperative for an implanted prosthetic heart valve to meet all therespective requirements for both the accuracy of the lateral positioningas well as the angular positioning.

In conventional implantation techniques in which self-expandingprosthetic heart valves are, for example, guided through a patient'sfemoral artery to the site of deployment at the heart in aminimally-invasive procedure, the prosthesis is usually introduced usinga guide wire and catheters, whereby conventional balloon catheters canalso be used. Although such a surgical introduction can be monitored andcontrolled, for example with fluoroscopy (Cardiac CatheterizationLaboratory=CCL) or with ultrasound (Transesophageal Echocardiogram=TEE),oftentimes—due to the limited maneuverability of the prosthetic heartvalve which is still in a collapsed state during the introductionprocedure and despite being in the collapsed state is still ofrelatively large size—it is not possible to ensure the requiredpositioning accuracy and especially the angular position to theprosthetic heart valve implant with the corresponding anchoring elementsaffixed thereto. In particular—as a result of a possible coronary arteryocclusion—an anglular misalignment to the implanted prosthetic heartvalve from the optimum site of deployment can pose a threat to therespective patient.

In designing a prosthetic heart valve, special consideration must, inparticular, be given to the substantial forces also acting on theprosthesis during the filling period of the cardiac cycle (diastole),necessitating a secure anchorage in order to prevent the implantedprosthetic heart valve from dislodging.

Hence on the one hand, the prosthetic heart valve must be able to bemaneuvered as much as possible in the respective coronary artery duringthe implantation procedure so as to ensure optimum positioning accuracyand, on the other hand, the implanted prosthesis must be able to befirmly anchored at its site of implantation in order to effectivelyprevent subsequent prosthesis misalignment.

The present invention addresses the problem that the known devices fortransvascular implantation and fixation of prosthetic heart valves areoften not suitable for easily implanting a prosthetic heart valve in apatient's ventricle with the necessary positioning accuracy. Inparticular, the necessary lateral positioning accuracy and the angularposition of the prosthetic heart valve can usually only be sufficientlyguaranteed when the person performing the procedure has thecorresponding experience. On the other hand, explanting a previouslyimplanted prosthetic heart valve in a minimally-invasive procedure oraccordingly correcting an incorrectly positioned prosthetic heart valvehas to date only been possible with great effort, if at all.

On the basis of this problem as set forth, the present inventionproposes a device which enables a prosthetic heart valve to be implantedinto a patient in a minimally-invasive procedure in as simple a manneras possible, wherein an increased positioning accuracy to the prosthesisin the patient's ventricle can in particular be ensured. Such a deviceis to, in particular, reduce the risk of an incorrect deployment to thegreatest extent possible.

SUMMARY OF THE INVENTION

According to the invention, this task is solved by a device as describedat the outset by the device having, in addition to the self-expandingheart valve stent with a prosthetic heart valve at its proximal end, aself-expanding positioning stent insertable into a position in thepatient's aortic valve, which is configured separate from the heartvalve stent, wherein the positioning stent and the heart valve stent areconfigured such that they each work in concert in their expanded statesso that the positioning stent helps to hold the heart valve stent in aposition relative the patient's heart valve predefined by thepositioning stent.

The device according to the invention exhibits an entire array ofsubstantial advantages over the prosthetic heart valves known from theprior art and described above. The two-part configuration of the devicein the design of the heart valve stent and the positioning stentconfigured separately therefrom can, in particular, greatly increase thepositioning accuracy of the prosthetic heart valve in the patient'sventricle. The positioning stent hereby primarily assumes the functionof determining the position of the prosthetic heart valve in thepatient's ventricle as well as the function of anchoring or fixing theprosthesis at optimum placement. In particular, the prosthetic heartvalve is not on or in the positioning stent, but instead configuredseparately from the positioning stent on the heart valve stent. This hasthe advantage that the dimensions of the positioning stent in itscollapsed state are extremely small, which increases the stent'smaneuverability.

The heart valve stent primarily serves the inventive device only as asupporting structure for the prosthetic heart valve to be implanted.This function sharing enables both the positioning stent as well as theheart valve stent to be of relatively simple configuration. What can beachieved in particular is that compared to a stent on which both aprosthetic heart valve as well as means for positioning and fixing theprosthetic heart valve are arranged, the positioning stent can beconfigured to exhibit only relatively small dimensions in its collapsedstate. Inserting the positioning stent in the patient's artery isthus—due to the better maneuverability achieved—substantially simpler. Adirect consequence of this is increased positioning accuracy for thepositioning stent.

The device according to the invention is configured in such a mannerthat not until the positioning stent is positioned into the patient'sartery and after aligning the stent with respect to a predefinable axialrotation and horizontal position relative an (old) heart valve of thepatient is the heart valve stent configured separately from thepositioning stent inserted into the artery or vein. During the insertionprocedure, the heart valve stent, which has the prosthetic heart valveat its proximal end, independently orientates itself to theexactly-positioned positioning stent as fixed at the arterial wall.Specifically, the heart valve stent is independently guided within theexpanded positioning stent into the implantation position predefined bythe positioning stent at which the prosthetic heart valve is in anoptimum position relative the patient's old heart valve. After the heartvalve stent, aided by the positioning stent, has positioned into thecoronary artery in the predefined position relative the old heart valve,the full expansion of the heart valve stent is induced, for example byan external manipulation, as a consequence of which the heart valvestent according to the invention interacts with the positioning stent insuch a way that the heart valve stent, and thus also the prostheticheart valve disposed at its proximal end, is positionally fixed into theimplantation position. Accordingly, the positioning stent serves—inaddition to the already mentioned function of defining the position forthe prosthetic heart valve in the patient's ventricle and the functionof anchoring or fixing the prosthesis at this position—also the functionof guiding the heart valve stent into the optimum position for theprosthetic heart valve during the implantation procedure. The advantagesattainable with the inventive device are obvious: in particular, anoptimum positioning is enabled for the prosthetic heart valve in itsfinal implanted position, whereby the alignment and fixing of theprosthetic heart valve ensues independently based on the co-operativeaction of the heart valve stent and the positioning stent. On the onehand, a position-contingent, inaccurate implantation of the prostheticheart valve can hereby be excluded. On the other hand, the device ischaracterized by the implantation and anchoring of the prosthetic heartvalve ensuing in a particularly simple manner.

Because the positioning stent according to the invention is configuredto be an insertable, self-expanding component in a patient's bloodvessel, it can be inserted beforehand; i.e., prior to the actualimplantation of the prosthetic heart valve disposed at the proximal endof the heart valve stent. It would thus be conceivable here for thepositioning stent to first be brought into the aorta and optimallypositioned and fixed there, whereby the heart valve stent with theprosthetic heart valve is thereafter introduced and inserted optimallyby means of the positioning stent already in position and fixed there.

According to the invention, both the heart valve stent as well as thepositioning stent are configured to self-expand, which facilitates therespective introduction of these components. Because the positioningstent assuming the task of determining the position for the heart valvestent, the prosthetic heart valve disposed thereon respectively, can beconfigured to be substantially smaller in comparison to previousself-expanding prosthetic heart valves, the maneuverability of thepositioning stent is increased considerably, which ultimately results inbeing able to select an extremely precise position at which thepositioning stent is anchored relative the heart valve and one ideallyadapted to the respective requirements. This advantage of exactpositioning of the easily-maneuvered and minutely-configured positioningstent extends to the subsequent implantation of the prosthetic heartvalve since the heart valve stent, at the proximal end of which theprosthetic heart valve is arranged, is held in the position defined bythe (optimally positioned) positioning stent.

Advantageous further developments of the inventive device are specifiedin the dependent claims.

One particularly advantageous development with respect to insertion ofthe heart valve stent provides for the heart valve stent to beconfigured to be reversibly expandable and collapsible. It is therebyconceivable for the heart valve stent to be collapsed, for example viaexternal manipulation, and extracted using an explantation catheter.Specifically, this embodiment enables the heart valve stent in collapsedform to be connectably received in a cartridge of a positioningcatheter, an explantation catheter respectively. In order for the heartvalve stent to be optimally inserted into a patient's blood vessel andpositioned there in a predefined position relative the heart valve, itis necessary for the positioning stent to be as small as possible in itscollapsed state so that the stent can be optimally navigated with aslittle impact as possible on the heart valve. This is achieved by theprosthetic heart valve implant not being affixed to the positioningstent but rather to the heart valve stent. The positioning stent isfurthermore configured such that all the components of the stent in thecollapsed state have a certain measure of pretensioning acting in aradially outward direction which effects the self-expansion followingrelease from the cartridge. The positioning stent can then be implantedwith the cartridge in conventional manner using a positioning stentcatheter, for example through a femoral artery. Should the positioningstent be inaccurately deployed, for example if the positioning stent isnot positioned precisely accurately in the patient's aorta, or when anexplantation of the positioning stent is necessary for other reasons, itis provided for the positioning stent to be convertible from itsexpanded state back into its collapsed state. This is done for exampleby external manipulation using an implantation catheter. The positioningstent is thus fully reversibly withdrawable in the catheter, whichenables the stent to be completely removed.

The inventive device for transvascular implantation and fixation ofprosthetic heart valves can advantageously provide for the positioningstent to have an anchorage at its proximal end, in particular ananchoring support, whereby this anchoring support is configured suchthat the positioning stent self-positions into a pre-defined positionrelative the patient's heart valve in its expanded state and is held bymeans of the anchoring support. The positioning stent is therebyconfigured such that the anchoring support is received in collapsed formin a cartridge connectable with a catheter. The anchoring support isthereby to be compressed such that it is pretensioned in a radiallyoutward direction which effects the self-expansion following releasefrom the cartridge. Configuring the positioning stent so that itself-positions into a given position relative the patient's heart valvein its expanded state and is held there by means of the anchoringsupport enables the position of the positioning stent and thus theposition of the heart valve stent to be precisely definable beforehandso that inaccurate implantations, as can occur with the known solutions,can be excluded.

In order to facilitate the positioning stent's self-expansion, thepositioning stent can advantageously furthermore exhibit pretensioningelements in order to radially pretension the positioning stent in itsposition defined by the anchorage. The pretensioning elements arethereby also configured to be reversible so that their pretensioningfunction can be countermanded by external manipulation, which enablesthe positioning stent to be collapsed and thus be retracted into acatheter, enabling the positioning stent to be removed completely.

An advantageous realization of the latter embodiment provides for theanchoring support to have at least one support strut which is configuredsuch that it self-positions into the pockets of the patient's heartvalve in the expanded state of the positioning stent and thus fixes theorientation of the positioning stent relative the heart valve in theaxial and horizontal direction. Hereby conceivable would be, forexample, that the support struts configured at the proximal end of thepositioning stent implant independently in the pockets of the respectivepatient's heart valve during the implantation procedure, whereby thepockets of the heart valve form a counter bearing for counteracting theproximal insertion motion so that the anchoring supports can beprecisely positioned laterally with the positioning stent. Since thepockets represent a guide per se for the support struts duringinsertion, this ensures at the same time that the anchoring support andthe positioning stent can adopt a precise angular position. Only afterthe support struts have been introduced into the pockets of therespective patient's heart valve and the final position for thepositioning stent has been reached is the heart valve stent configuredseparately from the positioning stent deployed with the help of, forexample, a heart valve catheter. The heart valve stent exhibiting theprosthetic heart valve at its proximal end is then optimally implantedat the most favorable and ideal site by means of the positioning stentalready having been exactly positioned and fixed. To be mentioned as afurther advantage is that the support struts of the positioning stentare positioned at the patient's heart valve following implantation ofthe positioning stent. Because the positioning stent is of relativelysimple configuration, since it for example does not comprise theprosthetic heart valve which is disposed separately from the positioningstent on the heart valve stent, the struts of the positioning stent canexhibit a relatively large radius, which entails a lesser risk of injuryto the heart valve.

The support strut disposed on an anchoring support or anchorage shouldbe curved convexly and arcuately in the proximal direction because sucha rounded form wards off injuries to the heart's blood vessel as well asfacilitates the unfolding in the self-expansion process. With such adesign, inserting the support struts into the pockets of the old heartvalve is thus likewise easier without engendering any correspondinginjuries to the tissue or the blood vessels of the region.

Additional stabilizing struts can also be provided on the anchoringsupports, which achieves increased fixedness following theself-expansion of the anchored anchoring supports. Such stabilizingstruts can be advantageous since in order to benefit from theself-expansion effect required of an anchoring support for securelyfixing the anchoring support with the positioning stent, accepting thatthe anchoring supports collapsed within a cartridge during theintroduction phase must be of the smallest volume possible, smallcross-sections for the respective struts must be maintained.

All the struts of an anchoring support should thereby be arranged,configured and dimensioned such that the successively ensuing release ofthe supporting struts and the other struts with the further elementsprovided on an anchoring support, as the case may be, can be achieved bythe appropriate manipulation of cartridge and/or catheter. In so doing,the design of the cartridge or at least a portion of the cartridgeshould, of course, also be taken into consideration.

Corresponding to physical anatomy, three supporting struts each arrangedat the same angular spacing from one another on the anchoring supportshould be provided. Yet there is also the possibility of arranging eachof the supporting struts disposed on an anchoring support to be at anangular offset from one another. In this case, the supporting strutswith their proximal members are then introduced into the pockets of anold heart valve in the implanted state and the old heart valve can thenbe tightly secured and fixed with the supporting struts.

The stability of an implanted and fixed positioning stent can beoptimally increased by means of at least one ring support, which can bean element on an anchoring support. Thus, by means of such a ringsupport, the possibility exists of connecting different struts providedon an anchoring support, preferably at their bases. It is thereby notimperative to provide a connection between the ring support and all thestruts of an anchoring support.

After the positioning stent is positioned at the heart and held there bythe anchorage, the heart valve stent is introduced. It is herebyadvantageously provided for the heart valve stent to be configured suchthat the prosthetic heart valve in its expanded state presses thepatient's heart valve against the aorta wall, whereby the at least oneanchorage of the positioning stent positions between the aorta wall andthe heart valve expanded by the prosthetic heart valve.

In order to have the heart valve stent be held in a position defined bythe positioning stent relative the patient's heart valve using thepositioning stent, the positioning stent has at least one engagingelement at its distal end. The heart valve stent should thereby exhibita correspondingly complementary-configured retaining element at itsdistal end, whereby in the expanded state of the positioning stent andin the fully expanded state of the heart valve stent, the at least oneretaining element forms a positive connection with the at least oneengaging element of the positioning stent. This thus achieves thepositioning of the prosthetic heart valve in the coronary artery in theposition predefined by the positioning stent and it being held there bythe positioning stent. It would hereby be conceivable to provideengaging clips on the heart valve stent. The engaging clips are therebyamong the elements of the heart valve stent which are not released toexpand until the heart valve stent is accurately inserted into itsimplantation deployment site at the patient's heart valve by means ofthe already implanted positioning stent. When the engaging clips of theheart valve stent expand, they engage with the engaging elements of thepositioning stent and thus hold the heart valve stent in the positiongiven by the positioning stent. At the same time, portions of therespective patient's old heart valve then each work into an anchoringstrut of the positioning stent and the expanded prosthetic heart valveso that the respective portions of the old heart valve can be clampedand held between these elements following the successful expanding ofthe prosthetic heart valve, similar to how a sheet of paper is heldbetween the brackets of a paper clip.

The heart valve stent is in particular configured such that it does notadopt its fully expanded state, in which both the prosthetic heart valveas well as also the retaining element is released, until the heart valvestent is in the position as defined by the positioning stent.

As is the case with the positioning stent, the heart valve stent is alsoadvantageously configured to be reversible in its folding action,whereby the positive connection with the positioning stent is disengagedin the collapsed state. This thus allows the prosthetic heart valvedisposed on the heart valve stent to again be explanted, for example inthe case of an improper implantation, without also having to extract thepositioning stent in order to do so.

In order to facilitate explantation of the heart valve stent,explantation elements can be provided at the distal end of the heartvalve stent which work in concert with the heart valve stent such thatwhen externally manipulated, for example, the explantation elementsdisengage the positive connection between the heart valve stent and thepositioning stent, and the heart valve stent collapses. One advantageousrealization of the explantation elements provides for their beingengageable, for example by means of an explantation catheter, wherebyretracting the explantation elements in the explantation catheterdisengages the positive connection between the heart valve stent and thepositioning stent, and the heart valve stent folds back up.

The heart valve stent is advantageously accommodated in the collapsedstate in a cartridge connectable to a heart valve stent catheter and/orexplantation catheter, whereby a predefinable motion of the cartridgewill release the heart valve stent. Specifically, it is therebyadvantageously provided that a predefinable first motion of thecartridge will only release the prosthetic heart valve to expand,whereby the retaining element of the heart valve stent is released by atleast one second subsequent motion of the cartridge, the catheterrespectively.

It can be advantageous, in particular for the subsequent cartridge andcatheter movement, which leads to the sequential release of theindividual elements of the heart valve stent, to use a multi-partcartridge, whereby at least two individual parts can each be movedrelative one another. Hence, the movements of a cartridge or individualparts of a cartridge to be realized, for example so as to lead toself-expansion, can be a proximal and/or distal displacement, which canensue in several successive stages, each covering different paths inorder to successively release the corresponding parts for theirrespective expansion during implantation.

Thus, a first movement, for example, can be a distal retraction of thecartridge or a portion of a cartridge. Should it hereby be necessary soas to avoid inaccurate implantation, a proximal movement of thecartridge or a portion of a cartridge can then be effected tore-collapse the already-expanded retaining elements acting radiallyoutwardly with a pretensioning force, the prosthetic heart valve of theheart valve stent respectively, and to bring same into the interior ofthe cartridge so as to enable the device to be removed from the patient.Bowden cables or flexible push tubes guided through the interior of thecatheter to the cartridge or to a portion of the cartridge can be usedas the actuating elements for a manipulation and the associateddisplacing movement of the cartridge or individual parts of thecartridge. Such actuating elements can, however, also engage withfastening elements, for example eyelets, provided on the anchoringsupport.

The solution according to the invention thus also provides thepossibility of aborting prosthetic heart valve implantations which willbe unsuccessful and removing the device again by withdrawing thecatheter, whereby in so doing, the heart valve stent which has alreadyexpanded re-collapses again and can be guided back into a cartridge or aportion of a cartridge.

An advantageous further development of the device according to theinvention provides for the positioning stent to furthermore compriseanchoring elements, in particular hooks, in order to anchor thepositioning stent in its predefinable position at the heart.Additionally or alternatively to the positioning stent, it would beconceivable for the heart valve stent to also comprise anchoringelements such as hooks, for example, in order to anchor the heart valvestent in the position in the aorta as predefined by the positioningstent. Both solutions ultimately serve the secure fixing of theimplanted prosthetic heart valve at its site of implantation aspredefined by the positioning stent.

In order to facilitate spatial orientation when inserting thepositioning stent, markers can be disposed on the positioning stent, inparticular x-ray markers. Of course, other solutions are alsoconceivable. For example, insertion of the positioning stent can also bemonitored and controlled using fluoroscopy (Cardiac CatheterizationLaboratory=CCL) or ultrasound (Transesophageal Echocardiogram=TEE).

The positioning stent and/or the heart valve stent can furthermoreexhibit guiding means which are configured in such a manner that theheart valve stent is guided independently in the expanded positioningstent into the position predefined by the positioning stent. It wouldhereby be conceivable for the guiding means to be configured as elementstapering to the distal end of the positioning stent, the heart valvestent respectively, so as to realize a self-adjusting of the heart valvestent in the positioning stent and thus into the position predefined bythe positioning stent.

The device according to the invention can also be used together with aballoon catheter. With a balloon catheter, the old heart valve can bepushed away prior to the self-expansion of the anchoring support.

The following will make reference to the figures in describing preferredembodiments of the device according to the invention for theimplantation and fixation of prosthetic heart valves in greater detail.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1: a preferred embodiment of a positioning stent of the deviceaccording to the invention in the inserted and expanded state;

FIG. 2A: a preferred embodiment of a heart valve stent of the deviceaccording to the invention in the expanded state;

FIG. 2B: the heart valve stent of FIG. 2A in the implanted state;

FIG. 3A,B: one schematic representation each to illustrate theexplantation process with a preferred embodiment of the heart valvestent, and

FIG. 4: a detailed representation of the explantation elements providedon the heart valve stent, the positioning stent respectively, as well astheir mode of operation.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

FIG. 1 shows a preferred embodiment of a positioning stent 20 for thedevice according to the invention in the inserted state. The positioningstent 20 is in its expanded state in the embodiment shown. As depicted,the positioning stent 20 has an anchoring segment 21′ with anchoringsupports 21 at its proximal end. The anchoring supports 21 are herebyconfigured such that they optimize themselves into the pockets T of theold heart valve relative to axial rotation as well as horizontalposition. To this end, the positioning stent 20 is supported by means ofanchoring supports 21 in pockets T of the old heart valve. The anchoringsupports 21 themselves are connected to docking segment 23 by means ofshoulders 22. The docking segment 24′ of positioning stent 20, providedat its distal end, exhibits a plurality of engaging elements 24 whichfix a heart valve stent to be implanted (not explicitly shown in FIG.1).

The positioning stent 20 is configured as a self-expanding component.Due to the simple configuration of positioning stent 20, whichessentially consists only of anchoring segment 21′, docking segment 24′and shoulders 22, the positioning stent 20 exhibits extremely smalldimensions when in its collapsed state. Thus, when inserting positioningstent 20, for example using a positioning stent catheter, thepositioning stent 20 has very good maneuverability within aorta A. Afterpositioning stent 20 has been inserted into aorta A, it is expanded,enabled, for example, by means of an external manipulation of thepositioning stent catheter. The anchoring supports 21 of the expandedpositioning stent 20 self-position into the pockets T of the patient'sheart valve, whereby the alignment of the positioning stent 20 in theaxial and horizontal direction is fixed relative the heart valve. Sothat the positioning stent 20 will expand independently, suitablepretensioning elements can be (optionally) provided. In the embodimentas shown, pretensioning elements are realized in the form of anchoringsupports 21.

After positioning stent 20 is inserted into aorta A and positioned andfixed there as described above, a heart valve stent 10 (FIG. 2A)disposed with a prosthetic heart valve 11 at its proximal end isinserted into positioning stent 20. It expands subsequent to releaseand, in doing so, presses the old valve against the aorta wall, thepositioning stent 20 respectively.

FIG. 2A shows a heart valve stent 10 in the expanded state. As'depicted, the heart valve stent 10 has the prosthetic heart valve 11 atits proximal end and an anchoring segment 12′ comprising at least oneretaining element 12 at its distal end.

FIG. 2B provides a representation of how the heart valve stent 10 isheld in the already positioned and fixed positioning stent 20. The heartvalve stent 10 is guided by guide elements 17, 27 in positioning stent20 relative to rotation and axial position such that the new heart valveis optimally positioned. Thereafter, further releasing of the heartvalve stent 10 introduces its anchoring segment 12′ into docking segment24′ (FIG. 1) of the positioning stent 20. The anchoring segment 12′comprises retaining elements 12 which form a positive connection withthe engaging elements 24 of the positioning stent 10 in order toposition the prosthetic heart valve 11 in the position in the coronaryartery as predefined by the positioning stent 20 and to hold same thereby means of positioning stent 20.

Unlike conventional heart valve stents, the heart valve stent 10 of thepresent device does not have retaining clips to engage behind the oldheart valve but rather engaging clips in the form of retaining elements12 in the anchoring segment 12′ of heart valve stent 10. These engagingclips interact with the engaging elements 24 disposed in the dockingsegment 24′ of positioning stent 20. The advantage of this is that theheart valve stent 10 is commutably anchored in positioning stent 20. Bymeans of its self-expanding induced by guide means 17, 27, heart valvestent 10 independently slides inside positioning stent 20 and cannotslide any further. The guide means 17, 27 are configured as elementstapering to the distal end of positioning stent 20 and/or heart valvestent 10. Due to the special design of engaging elements 23 ofpositioning stent 20 and the retaining elements 12 of heart valve stent10 as clips formed in zigzag fashion (Z-clips), a finer angularpositioning of the heart valve stent 10 can in particular ensue. Boththe positioning stent 20 as well as the heart valve stent 10 can beconfigured of individual segments, whereby the individual segments canbe rotated relative one another. This increases flexibility wheninserting the two stents into the aorta. It is in particular possible torealize a finer angular positioning to heart valve stent 10. It is thusconceivable, for example, for the physician to alternatively insert arotated prosthetic heart valve 11. The segmented configuration is alsoof advantage with respect to the collapsing of the heart valve stent andthe positioning stent since the segmented stents in collapsed state canbe housed compressed within a catheter.

FIGS. 3A, 3B and 4 are schematic representations of how the heart valvestent 10 in the already positioned and implanted positioning stent 20can be explanted. In the event of a valve dysfunction, the mechanicallystable connection between the positioning stent 20 and the heart valvestent 10 as described above can be disengaged again by externalmanipulation. This can be realized, for example, by using a catheter 30with a cartridge 33 affixed thereto to engage explantation elements 13.After retracting the explantation elements 13 into the variablefunnel-shaped explantation catheter 30, the heart valve stent 10 ispulled into same and can thus be replaced with a new one. Thepositioning stent 20 remains as a marking and anchoring base for a newheart valve stent 10. Positioning stent 20 can, of course, also beexplanted in a similar procedure.

The docking segment 24′ of the positioning stent can comprise eyelets ornubs to which the explantation catheter 30 is to be affixed in order toeffect such an explantation. Attaching to eyelets is possible viapreferably three to six eyelets and three to six loops which aresubsequently pulled out of the eyelets. The positioning stent 20 as wellas the heart valve stent 10 is in particular completely reversiblywithdrawable in the catheter, which enables the complete removal of thepositioning stent and/or the heart valve stent.

The disengaging of the mechanically stable connection betweenpositioning stent 20 and heart valve stent 10 by means of externalmanipulation, in the case of valve dysfunction for example, is possiblewhen the previously implanted heart valve stent 10 exhibits aretrievable structure suitable for this purpose. This could consist of aplurality of connecting struts which project medially from the upperouter end of the stent into the vascular lumen and join there with ananchoring device (eyelet, hook, nub, etc.). Should this anchoring devicenow be grasped by the retrieval catheter wire of catheter 30, the distalportion of heart valve stent 10 can thus be compressed toward the lumenand drawn into a catheter tube 33. This then again provides theopportunity of using the positioning stent 20 which remains as a markingand anchoring base for a new heart valve stent 10.

The positioning stent 20 is made from a solid mesh (wire, polymer, etc.)or produced in a laser-cutting process. Applicable as suitable materialsfor the positioning stent are NiTi, high-grade steel or biocompatibleplastics. For spatial orientation, x-ray markers can furthermore bedisposed on positioning stent 20.

1-18. (canceled)
 19. A medical system comprising: a valve prosthesiscomprising: a first stent component including a plurality of retainingelements and exactly three struts configured for placement within threerespective pockets of a native aortic valve upon implantation of thevalve prosthesis relative to the native aortic valve, wherein theexactly three struts extend in a proximal direction toward a nativeheart when the valve prosthesis is implanted relative to the nativeaortic valve; a second stent component including a plurality ofengagement elements corresponding to the plurality of retaining elementsof the first stent component; and a prosthetic valve component attachedto the second stent component; and a catheter containing the valveprosthesis in a collapsed configuration; wherein each of the first stentcomponent and the second stent component is self-expandable, the firststent component being self-expandable and releasable from the catheterindependent of self-expansion and release of the second stent componentfrom the catheter; and wherein the valve prosthesis is configured toreceive portions of the native aortic valve between the exactly threestruts of the first stent component and the second stent component uponimplantation of the valve prosthesis relative to the native aorticvalve.
 20. The system of claim 19, wherein the first stent componentincludes a plurality of fastening elements engaged with the catheter.21. The system of claim 20, wherein the plurality of fastening elementsincludes three eyelets.
 22. The system of claim 19, wherein the catheterincludes a multi-part cartridge that contains the valve prosthesis. 23.The system of claim 22, wherein the multi-part cartridge includes twoparts movable relative to each other.
 24. The system of claim 19,wherein the catheter is configured to effect a first predefined motionto release the first stent component, and a second predefined motionafter the first predefined motion to release the second stent component.25. The system of claim 19, wherein each of the exactly three struts iscurved arcuately in the proximal direction.
 26. The system of claim 19,wherein the catheter is flexible and configured to navigate through afemoral artery and an aortic arch of a patient.
 27. A medical systemcomprising: a valve prosthesis comprising: a first stent componentincluding a plurality of fastening elements and exactly three strutsconfigured for placement within three respective pockets of a nativeaortic valve upon implantation of the valve prosthesis relative to thenative aortic valve, wherein the exactly three struts extend in aproximal direction toward a native heart when the valve prosthesis isimplanted relative to the native aortic valve; a second stent componentincluding a plurality of engagement elements; and a prosthetic valvecomponent attached to the second stent component; and a cathetercomprising a multi-part cartridge containing the valve prosthesis in acollapsed configuration; wherein each of the first stent component andthe second stent component is self-expandable, the first stent componentbeing self-expandable and releasable from the catheter independent ofself-expansion and release of the second stent component from thecatheter; wherein the valve prosthesis is configured to receive portionsof the native aortic valve between the exactly three struts of the firststent component and the second stent component upon implantation of thevalve prosthesis relative to the native aortic valve; and wherein thefirst stent component is coupled to the second stent component via theplurality of engagement elements upon implantation of the valveprosthesis relative to the native aortic valve.
 28. The system of claim27, wherein the plurality of fastening elements includes three eyelets,each eyelet engaged with a portion of the catheter.
 29. The system ofclaim 27, wherein each of the exactly three struts is curved convexly inthe proximal direction.
 30. The system of claim 27, wherein each of theexactly three struts is V-shaped with an apex pointing in the proximaldirection.
 31. The system of claim 30, wherein the apices of the exactlythree struts are equidistant to one another.
 32. The system of claim 27,wherein the exactly three struts are configured to align the first stentcomponent with the native aortic valve in an axial direction.
 33. Thesystem of claim 27, wherein the plurality of engagement elements areconfigured to align the second stent component with the first stentcomponent.
 34. The system of claim 33, wherein the catheter is flexibleand configured to navigate through a femoral artery and an aortic archof a patient.
 35. A medical system comprising: a valve prosthesiscomprising: a first stent component including exactly three strutsconfigured for placement within three respective pockets of a nativeaortic valve upon implantation of the valve prosthesis relative to thenative aortic valve, wherein the exactly three struts extend in aproximal direction toward a native heart when the valve prosthesis isimplanted relative to the native aortic valve, the first stent componentbeing self-expandable; a second stent component including a plurality ofengagement elements, the second stent component being configured toself-expand radially inward of the first stent component after the firststent component is self-expanded; and a prosthetic valve componentattached to the second stent component; and a catheter comprising amulti-part cartridge containing the valve prosthesis in a collapsedconfiguration, the multi-part cartridge including two parts movablerelative to each other; wherein each of the first stent component andthe second stent component is self-expandable, and the first stentcomponent is releasable from the catheter independent of self-expansionand release of the second stent component from the catheter; wherein thecatheter is configured to release the first stent component beforereleasing the second stent component; and wherein the valve prosthesisis configured to receive portions of the native aortic valve radiallybetween the exactly three struts of the first stent component and thesecond stent component upon implantation of the valve prosthesisrelative to the native aortic valve.
 36. The system of claim 35, whereinthe catheter is configured to effect a first predefined motion torelease the first stent component, and a second predefined motion afterthe first predefined motion to release the second stent component. 37.The system of claim 35, wherein each of the exactly three struts iscurved arcuately in the proximal direction.
 38. The system of claim 35,wherein the first stent component includes three fastening elements,each fastening element being engaged with a portion of the catheter.